Abstract
Indoor and outdoor units of home-use air conditioner incorporate compact fans for heat exchange. Typical forms of these
fans are forward type sirocco fan, axial-flow type propeller fan and cross-flow type tangential fan. They are required to be
small enough for a given unit size and also to have an appropriate air flow rate, a lower noise level and a higher energy saving (fan efficiency). However, in designing the fan built in a newly developed air conditioner unit, it is generally difficult
to satisfy all of required conditions only by similarity law using known parameters of a prototype fan. Therefore, this study
aims to offer a modified, semi-empirical similarity law based on experimental data which enables us to give the fan with
better efficiency and lower noise, even though the geometrical shapes of each part of the fan may slightly differ from those
of the prototype fan.
